An aerogel is a solid state meso-porous material having open cells which has a porosity of 50% or more in volume. Typically, the aerogel is composed of 90 to 99.8% of air, with density ranging from 1.1 to about 150 mg/cm3. At the nanoscale, an aerogel structure resembles a sponge, and comprises a network structure of nanometer-sized voids connected with each other.
The aerogel can be made of various materials such as silica (SiO2), alumina (Al2O3), oxides of transition metal and lanthanide metal, metal chalcogenide including CdS and CdSe, organic and inorganic polymers, carbon, and the like.
An aerogel has, in general, an extremely high rigidity for its density, and can support a weight 2,000 times or more than the weight of itself. The aerogel also serves as an excellent thermal insulation material since it almost nullifies three factors of heat transmission, i.e. convection, conduction, and radiation. Furthermore, the aerogel serves as a good material for preventing heat convection, since air cannot circulate throughout the lattice. The aerogel works as a desiccating agent since it has a hygroscopic property.
Technologies concerning liquid crystals can be referred to Non-Patent Documents 1 and 2 mentioned below.
[Non-Patent Document 1] S. Urban, J. Przedmojski, and J. Czub, Liquid Crystals, Vol. 32, No. 5, pp. 619-624 (2005).
[Non-Patent Document 2] EKISHOUBINRAN (Handbook of liquid crystal), ed. by committee of EKISHOUBINRAN (Handbook of liquid crystal), published by MARUZEN on Oct. 30, 2000.